Sanitizing plastic material

ABSTRACT

AN EFFECTIVE AMOUNT OF NONIONIC TRIALKYLAMINE AND OPTIONALLY ONE OF A GROUP II-A OR GROUP II-B METAL SALT OF A MONOCARBOXYLIC ACID HAVING A CRABON CHAIN LENGTH OF 1 TO 4 CADMIUM CHLORIDE OR ETHYLENEDIAMINETETRACETIC ACID WHEN DISPERSED IN A THERMOPLASTIC RESIN IS AN EFFECTIVE AND LONG LASTING FUNGICIDAL AND BACTERICIDAL AGENT WHICH IS EFFECTIVE AGAINST BOTH GRAM-POSITIVE AND GRAMNEGATIVE ORGANISMS INCLUDING PSEUDOMONAS AERUGINOSA.

United States Patent C) 3,705,235 SANITIZING PLASTIC MATERIAL Robert H.McIntosh and Ezekiel H. Hull, Greensboro, N.C., assignors to PredictedEnvironments, Inc.,

Atlanta, Ga. No Drawing. Filed Apr. 30, 1971, Ser. No. 139,265 Int. Cl.A611 13/00 US. Cl. 424-83 4 Claims ABSTRACT OF THE DISCLOSURE Aneffective amount of nonionic trialkylamine and optionally one of a GroupII-A or Group II-B metal salt of a monocarboxylic acid having a carbonchain length of 1 to 4, cadmium chloride, or ethylenediaminetetraaceticacid when dispersed in a thermoplastic resin is an effective and longlasting fungicidal and bactericidal agent which is effective againstboth Gram-positive and Gramnegative organisms including Pseudomonasaeruginosa.

This invention relates to a self-sanitizing plastic material and to thesanitizing additive which is incorporated into a plastic material toproduce self-sanitizing characteristics in that material. Moreparticularly, the present invention concerns a plastic material and anadditive for use therein which will destroy or significantly reduce overalong period of time both Gram-negative and Grampositive bacteriaincluding Pseudomonas aeruginosa.

Through the present invention there is provided a selfsanitizing plasticmaterial, and a method of preparation thereof, which is effective inkilling or significantly inhibiting the growth of disease andinfection-producing micro-organisms which come into contact with thesurfaces of an article prepared from the plastic material. The plasticproduced according to this invention can be utilized in a manifoldnumber of molded objects which are designed to come within contact ofthe human skin. The term molded as used in this application is used inits broad sense to include forming generally under the usual hightemperatures encountered in organic plasticmaking techniques andencompasses other obvious forming methods such as potting, extruding,sheeting and the like. This self-santizing plastic material is ofincal'culable value in applications where the plastic comes into contactwith the skin of a human being or the mouth through the prevention ofpassage of many germs or disease-producing micro-organisms to the body.

The self-sanitizing plastic of this invention has the capacity to killmany types of bacteria, streptococci, fungi, and other disease-producingand infection-producing micro-organisms which might come into contactwith the surface of a molded object prepared from the material. Suchmicro-organisms are those which commonly cause communicable diseases,and in general the selfsanitizing plastic is fatal to organisms whichare classified bacteriologically as Gram-positive or Gram-negative. Inaddition, the plastic is specifically deadly to such organisms asPseudomonas aeruginosa.

The plastic material of this invention has the further ability tomaintgin its efiicacy after repeated washings, such as would be commonlyemployed in many applications. The longevity is measured in a period oftime which generally outlasts the life of most applied usages of theplastic.

Accordingly, it is a primary object of the present invention to providea plastic material which has a selfsanitizing characteristic over aperiod of time normally coextensive with the usable life of objectsprepared from the plastic material.

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Another object of the present invention is the provision of aself-sanitizing plastic material which may be used by human beings withno toxic or irritating effects.

Another object of the present invention is the provision of aself-sanitizing and non-toxic plastic material which may be preparedinto a number of physical shapes using conventional constructiontechniques.

Another object of the present invention is to provide a sanitizingadditive which may be formulated with thermoplastic materials and willnot degrade or otherwise reduce the physical properties of the plasticmaterial during fusion of the plastic material and subsequent usethereof.

These and other objects, features and advantages of the presentinvention will become apparent from a review of the following detaileddescription.

According to the present invention a self-sanitizing thermoplasticmaterial is provided for use in the manufacture of mattress covers, cribcovers, bassinet covers, draw sheets, cubicle curtains, pillow covers,emesis basins, toilet seats, shower curtains, male and female urinals,bed pans, bed pan liners, wash basins, carafes, tooth brushes, hairbrushes, combs, soap holders, denture cups, rolls of utility sheeting,catheters, drainage bags, colostomy pouches, ileostomy pouches, IVsolution bags, irrigation solution bags, blood bags, tubing,administration sets, donor sets, fountain syringes, enema bags, contactlens holders, examination equipment covers for all classes of tradeincluding a medical doctor, veterinarian, dentist, optometrist,ophthalmologist, and optician, moisture barrier for the building tradeto eliminate mold and mildew, table tops, food handling trays, wallpaneling, floor covering, carpet base, shower curtains, bath mats, andtelephone caps for month piece and reception unit.

The thermoplastic material of this invention includes a sanitizingadditive which is uniformly dispersed throughout the material. One ofthe most interesting and important features of this plastic material isits unique ability to release the sanitizing additive uniformly over thesurface of articles formed from the material and to replace thesanitizing additive when the surface concentration of the additive hasbeen reduced. The additive is homogeneously distributed throughout theplastic material. The additive migrates through the body of the plasticmaterial to continuously replenish the supply of additive on the surfaceof the plastic material to assure a long lasting surface concentrationsufficient to inhibit bacterial and fungal growth. Studies have shownthat even after an article is wiped or washed with soaps and detergents,the antibacterial and anti-fungal life span of the article is compatiblewith the normally anticipated useful life of the article.

It has been found that the active sanitizing additive migrates to thesurface of the thermoplastic article at a rate sufficient to maintain alevel of concenration that will inhibit the growth of a wide specrum ofcommon bacteria and fungi. Growth of the following organisms, includingboth Gram-negative and Gram-positive bacteria, has been found to beinhibited by the present self-sanitizing plastic material: sarcinalutea, staphylococcus aureus, staphylococcus albus, pseudomonwsaerugz'nosa, escherichia coli, klebsiella, candida albz'cans, salmonellachloraasius, enterobacter aerogenes, escherichia communior,streptococcus pyoge ncs.

The sanitizing additive of the present invention is a nonionic trialkylamine and optionally one of a Group I-I-A or Group II-B (from thePeriodic Table) metal salt of a monocarboxylic acid having a carbonchain length of 1 to 4, cadmium chloride, or ethylenediaminetetraaceticacid. Suitably, the trialkyl amine includes two alkyl groups which havea carbon chain length of 1 to 4 atoms and one alky group which has acarbon chain length of 8 to 18 9 atoms. Preferably, the trialkyl amineis a dimethylalkyl amine wherein the alkyl group has from to 14 carbonatoms. The most preferred amine in this invention isdimethyllaurylamine.

Suitably, the Group II-A or Group II-B metal salt of a monocarboxylicacid includes the barium, cadmium and strontium salts of acetic acid,propionic acid and butyric acid. The most preferred of these salts isbarium acetate.

The most preferred sanitizing additive is a mixture ofdimethyllaurylamine and barium acetate in a part by weight ratio rangeof 1:2 to 2:1 for acetate to amine. A preferred part by weight ratiorange for acetate to amine is 70 to 50 parts by weight to 30 to 50 partsby weight. A most preferred part by weight ratio is 60 parts amine to 40parts acetate.

When blending the additive into a plastic material, a suitableconcentration is 0.5% to 10% of additive in plastic by weight. Apreferred concentration is 2% to 9% and a particularly preferredconcentration is 3% to 7% by weight.

In preparing the amine-acetate sanitizing additive for incoroprationinto a plastic material, a mixture of dimethyllaurylamine and bariumacetate is most preferred. Granular barium acetate, of a particle sizeof approximately minus mesh 4 (U.S. Standard Screen Size), is added toan oily liquid dimethyllaurylamine in a part by weight ratio aspreviously discussed in a ball mill. The ball mill tumble-mixes andgrinds the mixture to a point where the particle sizes of the granularbarium acetate are reduced sufiiciently for the barium acetate to remainin suspension in the amine. Generally speaking, the acetate is reducedfrom minus 4 mesh to minus 325 mesh in the ball milling operation.

An appropriate amount of the amine-acetate suspension is then added to atumble-mixing machine containing a sufficient weight of thermoplasticpellets to produce a concentration of sanitizing additive in plastic asdiscussed previously. During the tumble mixing operation of the oilyamine provides a filmy coating on the plastic pellets which holds theground acetate on the pellets. As a result, the amine-acetate suspensionadheres to the pellets during the tumbling operation and there is noaccumulation or run-off of the amine-acetate suspension. The suspensionadheres to such a degree that the coated pellets may be stored for areasonabe period of time without run-off or separation of the suspensionfrom the pellets.

It has been found that thermoplastic materials are suitable for use inthe present invention. Of the available thermoplastics, polyolefins arepreferred and polyethylene and polypropylene are particularly preferred.When mixing the thermoplastic material with the amine-acetatesuspension, it is preferred that the plastics be initially in pelletform of approximately to A; of an inch in diameter. Pelletized plasticsare conventionally available from a number of suppliers.

After an appropriate amount of sanitizing additive is mixed with andcoated on a sufiicient quantity of pelletized plastic material, themixture is charged to a hopper of a conventional melt extruder where themixture is melted and the sanitizing additive is homogeneouslydistributed throughout the melted mass by the action of the extruder.The resultant molten mass of plastic material may be formed into adesisable shape such as disclosed previously. The molten mass may beformed into a sheet of plastic film and when such is done the sheet iseven in texture, translucent and contains a uniform dispersion of theadditive.

During the fusing operation in the melt extruder, temperatures as highas 230 C. may be employed without degradation of the sanitizingadditive. Preferably, the fusion temperature should be between about 150C. to 200 C. The sanitizing additive of this invention is quiteadvantageous for use in thermoplastics because it can withstand theheats of fusion required for most typical thermoplastics whereas knownsanitizing additives tend to degrade and discolor at these temperatures.

It has also been found that the molten mass from the melt extruder maybe passed through a conventional spinneret to generate thermoplasticfibers containing the sanitizing additive. These fibers may be gatheredtogether to form conventional threads and yarns for numerous uses.

The present invention will be further described by the followingexamples:

EXAMPLE I To parts of polyethylene pellets is added 10 parts of asanitizing additive comprising equal amounts of dimethyllaurylamine andbarium acetate. The pellets are coated with the oily suspension bytumbling mixing for twenty minutes. The coated pellets are fused in testtubes immersed in an oil bath at a temperature of C. to 202 C. fortwenty minutes. Upon subsequent cooling to ambient temeprature, theplastic cylinders from the test tubes are removed and sawed into discsapproximately 10 mils in thickness. No degradation of the polyethyleneis noted. The discs are placed within appropriately impregnated petridishes containing a nutrient agar. It is found upon incubation of thedishes that the discs inhibit the growth of bacteria and fungi aroundthe discs and create a zone of inhibition. The results for the listedorganisms are as follows:

TABLE A Organism: Zone of inhibition in ml. Sarcina leutea (1) Staph.aureus ll Pseudomonas aerugz'nosa 5 E. coli 5 Klebsiella l8 Candidaalbicans 8 Salmonella choleraesius 35 1 Complete inhibition throughoutpetri dish.

EXAMPLE II The procedure of Example I is repeated except that equalparts of ethylenediaminetetraacetic acid and dimethyllaurylamine areused as the sanitizing additive. The results obtained are as follows:

TABLE B Organism: Zone for inhibition in mi. Sarcina lutea 9 Staph.aureus 7 Pseudomonas aerugz'nosa 5 E. coli 5 Klebsiella 9 Candidaalbica-ns 7 Salmonella choleraesius 1O EXAMPLE III The procedure ofExample I is repeated except that equal parts of cadmium chloride anddimethyllaurylamine are used as the sanitizing additive. The resultsobtained are as follows:

TABLE C Organism: Zone for inhibition in ml. Sarcina luzea 10 Staph.aureus 10 Pseudomonas aeruginosa 10 E. coli l0 Klebsiella 15 Candidaalbicans 23 Salmonella choleraesias 45 While this invention has beendescribed in detail with particular reference to preferred embodimentsthereof, it will be understood that variations and modifications can beeffected within the spirit and scope of the invention als describedhereinbefore and as defined in the appended 0 arms.

We claim:

1. Process for preparing a self-sanitizing polyolefin thermo-plasticmaterial comprising the steps of:

(a) Tumble mixing and grinding together from 30 to 50 parts by weight ofbarium acetate with 70 to 50 parts by weight of dimethyllaurylamineuntil the barium acetate remains suspended in the dimethyllaurylamine;

(b) Adding from 2 parts to parts by weight of the amine/acetatesuspension to 100 parts by weight of thermoplastic polyolefin pellets ina tumble-mixing machine; and

(c) Melting the mixture of pellets and amine/acetate suspension to auniform self-sanitizing polyolefin thermo-plastic material useful tomold or extrude sheets, fibers, threads, yarns and other objects whichare designed to come into contact with human skin or be in closeassociation with human beings.

2. Process for preparing a self-sanitizing thermoplastic materialcomprising the steps of:

(a) Mixing together a nonionic trialkyl amine and a compound selectedfrom the group consisting of a Group II-A or Group II-B metal salt of amonocarboxylic acid having a carbon chain length of 1 to 4, or cadmiumchloride;

(b) Mixing an efiective amount of the mixture of step (a) with agranular thermo-plastic material; and

(c) Melting the mixture of step (b) to form a selfsanitizingthermo-plastic material.

3. Process of claim 2 wherein the nonionic trialkyl amine consists ofdimethyllaurylamine and the compound selected from the markush group isbarium acetate.

4. Process of claim 3 wherein from 2% to 10% by weight of the mixture ofdimethyllaurylamine and barium acetate is added to a pelletizedthermo-plastic material.

References Cited UNITED STATES PATENTS 3,567,119 3/1971 Wilbert 424-83 X3,454,510 7/1969 Newland et a1 424-83 X 3,324,201 6/1967 Peiser et al.424-83 X 3,096,183 7/1963 Genth 424-83 X 3,005,720 10/1961 TellOr 424-83X 2,919,200 12/1959 Dubin et a1. 424-83 X SHEP K. ROSE, Primary Examiner

